Upgrading ms office 2007 to 2019

There never was a "free" upgrade to newer versions of Office.

2010 was the last version that had a "loyalty" discounted "upgrade" from older versions.

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If you are looking to buy a one-time payment version of Office, ie Office 2019 Home and Student, you may want to consider holding off on that for a short time. MS has announced that they will be releasing Office 2021 "sometime this year".  They did October releases the last couple of times, so that is a good guess for this time.   You could do a 365 Personal monthly subscription until it comes out.

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But before doing that, talk around to your family (and "extended family", aka friends) to find out if anyone has a 365 Family subscription with one of the five allowed "shares".  Cheaper than buying. Best case a 6way share of 365 Family is $17 EACH per YEAR. Good deal.  Or someone who has 365 Personal and is willing to "upgrade". Even a 3way share makes it price competitive with the "new and (dis)improved" 5 year life of Office 2021. 

MS offers shares on 365 Family as a feature. More people should be aware of it and taking maximum advantage of this feature to make their subscription more cost effective. While it lasts.  Remember, when 365 was released in 2015 (along with Office 2016) it came with "unlimited" onedrive space. Yes, it really was unlimited. I considered ripping and uploading my DVD collection. Apparently a few people did exactly that. Just one year later MS announced an "improvement" to the subscription limiting OneDrive to 1TB per user.  Some improvement.  I expect the "share" count to go down eventually. 

Each person with a Share is completely independent and secure from the owner and the others. All the owner can do is remove the share, they do not have access to anything belong to people they grant shares to.

Unfortunately, no. There are no "upgrade" licenses of Office anymore.

For an overview of what is being offered, see https://www.microsoft.com/en-us/microsoft-365/buy/compare-all-microsoft-365-products. Of course, perpetual (one-time payment) licenses such as Office Home & Student or Office Home & Business will be cheaper than the subscriptions. Note that perpetual licenses are for a single user and a single computer.