Honest arithmetic
The case for not subscribing
Worth putting first, because the answer is genuinely no for some people.
If you need one conversion, once, a subscription is a poor fit even at an intro price — you will forget to cancel and pay for months you did not use. That is the mechanism behind most regret in this category, and it is not specific to this product.
The case for
It changes at frequency. Someone handling documents weekly — invoices out, statements in, contracts to sign and send — crosses the line quickly, because the alternative is either a desktop suite at several times the price or twenty minutes of manual work per document.
The test
Count the documents you handled last month. If the answer is one, do it by hand. If it is more than four, the arithmetic has already decided.