Wait until you want to convert the UG to a GmbH and realize that it's not simple or cheap at all.

It's not enough to have had properly filed tax returns every year, have a large enough profit-collection-line item in your books (25k EUR+) and then fill out a form.

No, if you want to use the profit your UG was required to accrue to raise your capital stock to 25k and rename it to a GmbH you need to get your annual accounts audited.

Or alternatively, you can pay in the difference between your current capital stock (e.g. 2k) and the 25k minimum for the UG and then rename the company and "just" have to pay for the notary, publishing to public records, court, ...